Like previously mentioned Backdrop or the Windows-only Dropcloth, Camouflage is intended to block out a cluttered desktop to avoid distraction. However, it's got a few interesting features that improve on the others, like the ability to still interact with your desktop via drag-and-drop, and integration with Finder (through the "Clickthrough" and "Popup Desktop" features). My favorite feature, though, is user-defined keyboard shortcut, which lets you toggle between showing and hiding your desktop icons. This won't be for everyone, but if you like what Backdrop and Dropcloth do, this app might have a place in your menubar. Camouflage is donationware, Mac OS X only.